Search

In this paper, we investigate the realization of synchronized spread spectrum code division multiple access (synchronized SS-CDMA) for the quasi-zenith satellite system (QZSS) safety confirmation system during major disasters. The QZSS is expected to provide a highly accurate positioning service and allow two-way communication, which includes the terminal location and short messages. The proposed synchronized SS-CDMA scheme realizes direct access from mobile terminals to the satellite and the simultaneous transmission of many users using SS codes with a large spreading factor. All terminals synchronize their own clock and frequency with those of the global navigation satellite system (GNSS). In this scheme, maintaining orthogonality among users in both the time and frequency domains is the most important problem. In this paper, for the consideration of mobile use, the effect of residual timing jitter and frequency offset in a fading environment is evaluated by computer simulation. As a result, acceptable timing and frequency errors for terminals are clarified in order for the system to be viable using the GNSS.

We propose “Extended Dependable Air” as a highly reliable wireless network. Extended Dependable Air can be used in the “3S” areas: space, surface, and sea. For the implementation of the Extended Dependable Air, two key technologies using satellite systems such as the Quasi-Zenith Satellite System (QZSS) and the Global Positioning System (GPS) are proposed; One is a QZSS Spread Spectrum Code Division Multiple Access (SS-CDMA) short-message communication system, and the other is a heterogeneous wireless system with a network selection scheme using positioning information. The former, the QZSS SS-CDMA short-message communication system, is proposed for large-scale disaster relief. The target capacity of the proposed system is the transmission of at least three million message data per hour. Because this method provides high-density user multiplexing using long spread codes in the uplink, highly accurate timing and frequency synchronization among all terminals is the most important issue. SS-CDMA ensures the use of QZSS positioning signals and maintains the orthogonality in the time and frequency domains among all the codes transmitted from terminals. The latter, the heterogeneous wireless systems, are candidates for achieving a large capacity in next-generation mobile communication systems. In this section, we propose a cell selection scheme for data traffic optimization in heterogeneous wireless systems. The proposed scheme uses high-accuracy positioning information and the average signal strength for cell selection. Using positioning information, users can select a cell with the highest channel quality quickly and easily. It is considered that the proposed scheme will be useful for optimizing data traffic offloading in heterogeneous wireless networks.

This chapter deals with the issue of timing and synchronicity, which is fundamental in the architecture design of computer, communication, and control systems. In fact, if a signal took too long to travel from one point in a system to another exceeding the predetermined length of time, then the system would involve an error, fault, or failure. An electromechanical robot would lose intended integrity in coordinated limb motions without responsive signals arriving in time from elsewhere in its distributed hard real-time control system. Successful delivery of a universal clock signal would be indispensable for distributed coupled computer-and-communication systems for real-time financial transactions. Section 9.1 describes the requirements in hard real-time control system such as industrial and humanoid robots. Section 9.2 is a proposal of a computer architecture for hard real-time control that is capable of pre-emptive multiple-thread computation on demand and noise-immune communications between distributed sensor–actuator nodes. This architecture, called RMTP (Real-Time Multithread Processor), has been implemented in compact 3-D modules and made available for academic uses along with the design tools. Section 9.3 describes asynchronous networks which can efficiently and reliably connect on-chip and off-chip functions in a distributed system against timing errors. The use of a global synchronization in public wireless telecommunication is proposed in Sect. 9.4 to provide dependable connectivity and maximized throughput using the satellites and cellular base stations with heterogeneous air interfaces.

Good connection quality is a most important requirement in telecommunication systems. For the public wireless network, however, primary attention has so far been paid to providing broader bandwidth for rapidly expanding subscriber base. In this chapter, the connectivity of wireless telecommunication is undertaken as a central issue, while keeping in mind that the next-generation wireless will take on broader and ubiquitous machine-to-machine (M2M) applications, and that the communication traffic will be 1000 times heavier in 10 years. The reliability and dependability will be a must in future wireless communications. The devastation caused by the East Japan Earthquake in March 2011, when few people in the area could use mobile phones satisfactorily because of the significant damages in infrastructure, taught a lesson that the wireless connection has to be maintained even in time of emergency. In this chapter, we will discuss heterogeneous wireless network that is combination of multiple wireless systems, e.g., cellular phone system, Wi-Fi, and wireless personal area network (WPAN) for realizing high-connectivity wireless network. The technology base that we have developed to enables the dependable heterogeneous network will be discussed in detail. All Silicon complementary metal oxide semiconductor (CMOS) technology will be used for analog/radio frequency (RF) circuits and baseband technologies for carrier frequencies from 700 to 60 GHz. A novel frequency domain equalizer (FDE) implemented in an application-specific integrated circuit (ASIC) will be a key component for smooth system handover. A scalable, low-voltage, and adaptive analog-to-digital (A/D) converter will be discussed as well.

A 60-GHz band planar dipole array antenna structure in a small wireless terminal is proposed for wide coverage area beamforming applications. Several substrates are stacked vertically by using 3-D system-in-package (SiP) technology, and the element antenna is installed on the substrates. A planar dipole antenna is used as an element antenna because it has a wider bandwidth than conventional patch antennas, which are widely used in 60-GHz band beamforming applications. Conventional dipole array antennas have a 1-D structure, or a 2-D structure arranged in multilayered substrate, resulting in narrow beamforming coverage area. The proposed structure has a wide beamforming coverage area because of the wide antenna spacing around 0.5λ0. Design using numerical and 3-D electromagnetic field simulation indicate that a 4×2 arrangement is a feasible structure for a small wireless terminal with wide coverage area. Measurement results show that the designed array antenna has a wide coverage area, covering 75 and 95 in the theta and phi directions, respectively, with gain exceeding 10 dBi. The proposed planar dipole array structure using 3-D SiP technology is feasible as a 60-GHz band 2-D beamforming antenna in small wireless terminals.

To deal with the explosion of wireless traffic, the authors are now considering a new system at 3.5 GHz band, which consists of small outdoor cells constructed by access points set up indoor. In order to utilize this system, measurement-based propagation modeling in multiple frequencies is necessary. In this paper, the authors propose the new modeling method for indoor-outdoor propagation when buildings are arranged side-by-side in parallel. Additionally, the authors derive a fitting parameter at 2.5GHz and 3.5 GHz in order to compare characteristics of the target frequency with those of a frequency in service. The result shows that indoor obstacles have notable effect to path loss exponent whereas little effect to a path loss offset, while a path loss offset has a dominant effect when it comes to a difference of a frequency. Moreover, the authors confirm our model can predict a shadow fading accurately compared with previous indoor-outdoor propagation model.

We have proposed spread spectrum code division multiple access (SS-CDMA) short message communication using Quasi-Zenith Satellite System (QZSS) as a safety confirmation system at the time of great disaster. Highly accurate timing and frequency synchronization among all mobile terminals (MTs) is necessary for the synchronized SS-CDMA system to provide high density user multiplexing using long spreading codes in uplink. In order to synchronize the timing that the satellites receive uplink signals, each MT controls its own timing and frequency at the timing of each transmission using QZS and Global Positioning System (GPS) signals. Particularly the number of visible satellites can have a major impact on the time synchronization. In this paper, we evaluated the time synchronization accuracy in the synchronized SS-CDMA system experimentally. The results show that it is possible to achieve accommodation rate of short message system of 100 % when the elevation mask is 30 degrees.

This paper proposes a heterogeneous wireless network with handover in the application layer. The proposed network requires no upgrade of wireless infrastructure and mobile terminals to convert the present homogeneous networks to the proposed heterogeneous network. Only installing application programs on the content server side and the mobile terminal side is required. The performance of the proposed network has been evaluated in a field trial using a mobile broadband wireless access (MBWA) air interface with wide coverage and a wireless local area network (WLAN) air interface with high throughput. The field trial results show that the maximum value of the handover outage time is only 170ms. The proposed heterogeneous wireless network is promising since both high throughput and wide coverage area are attained by a combination of the proposed handover scheme with the present homogeneous wireless networks.

In this paper, low phase noise 5GHz oscillator is presented. This oscillators designed with 90nm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, we used high Q value film bulk acoustic resonator (FBAR) instead of conventional LC resonant circuit. This FBAR oscillator has phase noise of lower than -130dBc/Hz at 1MHz offset.

In this paper, a fully integrated 5GHz voltage controlled oscillator (VCO) is presented. The VCO is designed with 0.18µm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, a novel varactors pair circuit is proposed to cancel effects of capacitance fluctuation that makes harmonic currents which increase phase noise of VCO. The VCO with the proposed varactor circuit has tuning range from 5.1GHz to 6.1GHz (relative value of 17.9%) and phase noise of lower than −110.8dBc/Hz at 1MHz offset over the full tuning range. Figure-of-merit-with-tuning-range (FOMT) of the proposed VCO is −182dBc/Hz.

SUMMARY The self-timed pipeline (STP) is one of the most promising VLSI/SoC architectures. It achieves efficient utilization of tens of billions of transistors, consumes ultra low power, and is easy-to-design because of its signal integrity and low electro-magnetic interference. These basic features of the STP have been proven by the development of selftimed data-driven multimedia processors, DDMP’s. This paper proposes a novel scheme of interacting self-timed (clockless) pipelines by which the various distributed and interconnected pipelines can achieve highly functional stream processing in future giga-transistor chips. The paper also proposes a set of elementary coupling control modules that facilitate various combinations of flow-thru processing between pipelines, and then discusses the practicality of the proposed scheme through the LSI design of application modules such as a priority-based queue, a mutual interconnec

A 5GHz differential power amplifier (PA) module with a dipole antenna has been implemented. The PA integrated circuit (IC) was mounted on a fluoroplastic substrate on which the dipole antenna was fabricated. The differential PA IC was fabricated using 0.18µm Si-CMOS process. For the differential operation, an n/nMOS push-pull circuit was employed. The PA IC was directly connected to the balance input of dipole antenna without a balun using stud bump bonding on a fluoroplastic substrate. The antenna was designed using a 3-dimensional electromagnetic simulator including a feed line. The measured gain of the PA module was 12.6dB at 5GHz.

Direct RF under sampling reception has been developed to reduce the size and the power consumption of the terrestrial wireless terminals. We applied this reception method to Ku-band very small aperture terminal (VSAT). In this paper, we develop a CMOS sample and hold (S/H) IC for Ka-band VSAT receiver. Since Ka-band VSAT requires higher RF frequency operation (19.4–20.2 GHz) and wider system bandwidth (800 MHz) than the Ku-band one, high isolation series/shunt sampling switch, reactive on-chip matching circuit for RF input and high speed sampling clock circuit are needed. The proposed S/H IC is designed and fabricated in 90 nm CMOS process. The fabricated IC performs the |S11| of lower than −19.4 dB and the signal-to-noise ratio (SNR) of higher than 27.3 dB in the reception system bandwidth of Ka-band VSAT (19.4–20.2 GHz).

Heterogeneous wireless systems such as a combination of mobile broadband wireless access (MBWA) and wireless local area network (WLAN) are candidates to attain the large capacity in next generation mobile communication systems. For capacity expansion, small cell networks using millimeter wave are necessary. However, small cell networks have only several meters coverage, thus their resources are used by only a small part of traffic. In this paper, we propose the traffic navigation using the high accuracy positioning information and channel quality & traffic maps. In the proposed scheme, each user terminal schedules the timing of the data packet transmission on the basis of the expected user's route. Using the proposed traffic navigation, the system-wide load balancing can be realized. The simulation result shows that the proposed scheme can improve the system throughput in comparison with the conventional one.

For the next-generation mobile communication, heterogeneous wireless networks have been discussed to attain high throughput and wide coverage. In heterogeneous wireless networks, wireless local area network (WLAN) is important as a destination to offload traffic. However, hidden terminal problem and exposed terminal problem of WLAN become seriously in high user-density, high traffic demand and multicell environments. In this paper, we propose a virtual sector method using location information to solve these problems. The key point of the proposal method is that highly accurate location information of mobile terminals (MTs) is used without collecting location information by a controller. The method is able to be realized by a simple terminal-led control with a little assist from network keeping carrier sense multiple access with collision avoidance (CSMA/CA). As a result of computer simulation, the proposal method improves system throughput up to twice or more compared with usual CSMA/CA in high traffic demand situation.

To reduce the size and the power consumption of receivers, direct RF under sampling reception has been developed. This reception method is applicable for satellite communication receivers, because the requirements of near-far resistance and spurious response can be relaxed from that of terrestrial wireless receivers. In this paper, we propose and demonstrate a Ku-band series/shunt switching type sample and hold (S/H) IC for very small aperture terminal (VSAT) RF under sampling receivers. The series/shunt configuration enables low RF signal leakage to the S/H output during hold period even in the high frequency range. To reduce to the loss of input stage of the S/H IC, parallel resonant inductor is attached to the shunt switch FET and on-chip matching circuit is employed for RF input port. The proposed S/H circuit is designed and fabricated in 90 nm CMOS process. The fabricated IC performs the |S11| of lower than −19dB and the signal-to-noise ratio (SNR) of higher than 34.9 dB at VSAT's Ku-band (12.2–12.75GHz).

This paper presents an optimum interstage matching inductor of a cascode amplifier by formulation, for the first time. The formulation clarifies capacitances of FETs which degrade a gain of the cascode amplifier. The inductive matched cascode LNA fabricated by 90nm CMOS performs 25.6 dB gain with NF of 6 dB and output P1dB of −2.3 dBm at 60GHz while consuming 26.9 mW.

Recently, RFIC flip-chip mounting technique is very important to make small size and high frequency transceivers like mobile phones. The conventional flip-chip mounting uses Au stud bump bonding (SBB) and requires complicated process which includes forming and leveling of the bumps. In order to simplify the RFIC flip-chip process, we introduce a fiber type anisotropic conductive film (ACF) adhesive. This flip-chip mounting process does not require the SBB process and is suitable for transceiver system RFIC's having large number I/O pins. The interconnection between the RFIC and the substrate is confirmed by the 3D-CT images. The RF performance of the interconnection is measured and analyzed. The measured return loss of this interconnection is more than 10dB below 4.2GHz.

Self-directed beamforming system is to calculate phase difference from signals received at each element of the array antennas with digital signal processing and estimate the direction of arrival of the signal, and form a main beam to the direction. When conventional self-directed beamforming method is applied to broadband communication, the processing of broadband signals as many as antenna elements is required, thus it is difficult to add the method to mobile terminals. We have proposed self-directed beamforming method easily applied to broadband communication. In this method beams were controlled with phase information extracted from low frequency component of received signal. In this paper, prior to verification at RF-band, IF receiver modules were fabricated and the correct operation of the proposed method was confirmed. BF experiment using 2Gbps QPSK signal assuming IEEE 802.15.3c was performed. As a result of synthesis of four IF modules, improvement of the SNR approximately proportional to the number of the synthesized modules was confirmed.

A 0.8–1.9 GHz direct digital radio frequency (RF) quadrature modulator is designed and fabricated in 90 nm CMOS process. The bit number and the CLK frequency of I/Q digital input signals are designed to satisfy the required EVM, ACPR/NACPR and system bandwidth for 0.9/1.9GHz W-CDMA terminals. The fabricated quadrature modulator performs EVM of less than −22.7dB, ACP/NACP of less than −36.1dBc and spurious free range of 197MHz (wider than the W-CDMA system bandwidth of 60MHz) with 8-bit, 100Msps I/Q digital input signals and the d.c. power consumption of 10mW.

Heterogeneous wireless systems such as a combination of mobile broadband wireless access (MBWA) and wireless local area network (WLAN) are candidates to attain the large capacity in the next generation mobile communication systems. For capacity expansion, small cells of multiple wireless network are deployed densely in these systems. Because a number of the cells overlap, users must discover a lot of cells at once for cell selection. As a result, radio resources are much used for cell discovery in dense small cell environment. We have proposed the efficient network selection scheme using the positioning information and the map information. Using the map information, users can select the cell which has a better channel quality without cell discovery. In this paper, for further enhancement of system performance, new selection scheme considering the traffic load is evaluated. Using this load information, user select a network based on the expected throughput and their location. Consequently, users can avoid the congested network and select one which has a low traffic demand. We discuss the user throughput of the proposed scheme by comparing with the conventional one where users select by measured instantaneous signal strength. The simulation results show that the proposed scheme can improve the average user throughput by 52.8% in comparison with the conventional one. These performances can be achieved by feasible positioning accuracy.

We have proposed a switched-current (SI) analog programmable finite-impulse-response (FIR) filter for software-defined radio. The programmable tap coefficient circuit for programmable operation of the SI FIR filter has also been proposed. The 4-bit-resolution tap coefficient circuit has been designed and fabricated using 0.35 µm complementary-metal-oxide-semiconductor technology. The current error between measured and calculated tap coefficient circuits has been less than 2%. The radio frequency/intermediate frequency SI band-pass filter has been designed using the measured tap coefficients. The designed SI FIR filter has a frequency response as well as calculated tap coefficients. The maximum operating frequency of the proposed SI FIR filter using 0.13 µm CMOS technology has been estimated to be greater than 10 GHz with circuit simulation.

A linearity enhancement technique to a CMOS triple cascode push-pull power amplifier (PA) by second harmonic feedback has been proposed. The Second harmonic feedback is optimized to improve linearity based on the concept that the linearity is depend on the second harmonic feedback amplitude and phase. In order to feed second harmonics back to the push-pull PAs, we adopt a balun with a branching filter fabricated by using multi-layered organic substrates. The PA was fabricated in 0.18-µm CMOS process and was implemented on the balun by flip-chip connection. Because of the low breakdown voltage of CMOS power transistors, triple cascode configuration was adapted. It has been demonstrated that using second harmonic feedback, PAE and output power with a wideband code division multiple access (WCDMA) modulated signal are improved by 5.3% and 2.5dB respectively at adjacent channel leakage power ratio (ACLR) of −39dBc, and it has been demonstrated PAE of 28.8% and output power of 24.5dBm, respectively.

Heterogeneous wireless systems such as a combination of mobile broadband wireless access (MBWA) and wireless local area network (WLAN) are candidates to attain the large capacity in the next generation mobile communication systems. For capacity expansion, small cells of multiple wireless network are deployed densely in these systems. Because a number of the cells overlap, users must discover lots of cells at once for cell selection. As a result, radio resources are much used for cell selection and cell selection errors occur in dense small cell environment. In this paper, we propose the cell selection scheme for data traffic optimization in such an environment. The proposed scheme uses positioning information and the average of signal strength for cell selection. Using positioning information, users can select the cell which has a better channel quality fast and easily. It is considered that the proposed scheme is useful to optimize data traffic offloading in the heterogeneous wireless network. We study the 50 % user throughput and the system throughput of the proposed scheme by comparing with the conventional scheme which uses measured instantaneous signal strength. The simulation results show that the proposed scheme can improve the 50 % user throughput by 68% in comparison with the conventional scheme. Also, the system throughput is enhanced by 10 % compared with the conventional scheme. These performances can be achieved by feasible positioning accuracy.

In WLAN systems, distributed coordination function (DCF) is used to avoid transmission collision. When an error occurs, the transmitter extends its contention window for the next retransmission to avoid more errors. But this may cause an unfairness problem; in noisy conditions MTs may find it difficult to get transmission opportunities, especially in a heterogeneous network with a large number of WLAN access points (AP). In this paper, a new control scheme with separate control channel for WLAN is proposed. When a receiver detects a transmission error, it replies special signal via the control channel to abort transmission of corrupted data. This way the transmission of corrupted data can be reduced. Thus the it is no longer necessary to change contention window size and all MTs have the same probability to get transmission opportunities. The simulation results show that by using this technique, the average throughput of MTs whose packet error rates (PER) are larger than 0.3 can be at least 2 times compared with conventional scheme.

The superiority of dimethylaluminumhydride [(CH 3 ) 2 AlH, DMAH] to dimethylethylaminealane [AlH 3 N(CH 3 ) 2 (C 2 H 5 ), DMEAA] has been investigated from the view point of aluminum chemical vapor deposition (Al CVD) technology in ULSI manufacturing. Both DMAH and DMEAA have the same filling capability such as surface morphology and step coverage. For deposition reproducibility, the smaller activation energy is more suitable for manufacturing. The activation energy of Al deposition is found to be 0.38 [eV] for DMAH and 0.74 [eV] for DMEAA. These results mean the reproducibility of Al thickness using DMAH is superior to that using DMEAA. For safe storage and precise precursor delivery, the precursor should be chemically stable. From the results of measuring the pressure increase in vessel, it has shown that DMAH has superior chemical stability to DMEAA. Manufacturing apparatus such as Al CVD cluster module requires the deposition selectivity that is defined as Al deposition only on the desired areas of wafer surface and not on any parts of cluster module. Using DMAH, Al is deposited on barrier metal surface of silicon wafer, while Al is not deposited on the sealed anodic oxidized aluminum or the synthetic quartz. DMAH has shown excellent selectivity in comparison with DMEAA. Therefore, DMAH is superior to DMEAA as a precursor for the Al CVD technology in ULSI manufacturing.

A 60GHz band 3-dimensional (3-D) phased array antenna module has been fabricated and hetero-plane beam synthesis is demonstrated. Two separated 2×2 end-fire dipole array antennas in different (z-y and z-x) planes are configured in a multi-stacked substrate module. For x-direction, z-y plane array antenna is used and for y-direction, z-x plane array antenna is used. In order to achieve higher antenna gain at intermediate region between x and y directions, hetero-plane beam synthesis is employed using two array antennas in different (z-y and z-x) planes. Measured radiation patterns are in agreement with simulated radiation patterns and wider 10 dBi beam coverage area of 150° in azimuth and 60° in elevation is obtained. The results show the effectiveness of proposed hetero-plane beam synthesis.

The (1 1 02) α-Al2O3 surface and the initial nitriding AlN layer are investigated using the atomic-force microscope. The initial nitriding method is to convert the (1 1 02) α-Al2O3 surface to a nanometer-thick AlN single-crystal buffer layer. The epitaxial AlN film is deposited by metalorganic chemical vapor deposition with and without the initial nitriding. Atomic step structure is found to be formed after the H2 annealing. The atomic step structure is maintained during the initial nitriding time up to 5 min. Smooth AlN epitaxial films have been successfully deposited on the 2 inch diameter (1 1 02) α-Al2O3 wafer without any inverse-twin throughout the wafer by keeping the atomic step structure of the initial nitriding buffer layer.

In order to extend the communication range of the 60-GHz band broadband communication system, beam forming technology has been introduced. Due to the relatively high insertion loss and high phase/amplitude errors of 60-GHz band radio frequency (RF) phase shifter, broadband base band (BB) phase shifter has been focused. In this paper, we have developed a beam forming CMOS receiver RF integrated circuits (RFIC) with 5-bit BB phase shifter for the use in phased array antenna (PAA) receiver module employing 3-dimensional (3-D) system in package (SiP) technology. The receiver RFIC consists of a 7-stages low noise amplifier (LNA), an on-chip balun, a down-mixer, a quadrature-mixer, and a 5bit BB phase shifter. To obtain the broadband characteristic of 2 GHz at RF (i.e., 1 GHz at BB), BB phase shifter has been carefully designed. By using fixed-gain amplifier matrix configuration instead of variable gain amplifiers, broadband and low phase/amplitude errors are obtained. The fabricated receiver RFIC in 90-nm CMOS process exhibits performance applicable to 60-GHz band broadband communication such as IEEE 802.15.3c (channel 2).

In conventional RF under sampling front ends the sampling frequency is greater than the anti-aliasing filter's bandwidth, which is usually larger than the desired signals bandwidth. In this paper a technique for lowering the sampling frequency required for an RF under sampling receiver is presented. Mathematical expressions to ensure that signal integrity is preserved have been derived. Using these expressions the minimum sampling frequency required is halved. To validate the technique, simulation and measurement of a front-end using the conventional and the proposed techniques has been performed. In the simulation the conventional and proposed techniques achieved SNRs of 22.8 dB and 22.4 dB respectively. The measured SNR for the conventional technique was 19.8 dB and 20.3 dB for the proposed. Using QPSK modulation the EVM was measured to be -19.8 dB for the conventional and -19.5 dB for the proposed techniques.

Heterogeneous wireless systems such as a combination of mobile broadband wireless access (MBWA) and wireless local area network (WLAN) are candidates to attain higher throughput and wide coverage in the next generation mobile communication systems. A multimode receiver to demodulate signals with multiple air interfaces is required in the heterogeneous systems. In this paper, we discuss an implementation of frequency domain equalizer (FDE) in the multimode receiver on an application specific integrated circuit (ASIC). The proposed multimode FDE could realize adaptively demodulate two systems (single carrier and multi carrier) depending on propagation environment. A multimode FDE ASIC is designed and implemented on 180-nm complementary metal-oxide semiconductor (CMOS). Core size of multimode FDE chip is 17.6 mm2. The experimental results show that the ASIC yields a throughput of 48.1 Mbit/s at a sampling rate of 100 MHz. The results also show that the power penalty of the measured bit error rate (BER) performance is only 1 dB at a BER of 10-3 in a 4-paths Rayleigh fading channel. We consider that the implemented ASIC is useful to demodulate signals with different air interfaces while optimally selecting an appropriate air interface in the heterogeneous wireless system.

A 5 GHz-band direct digital radio frequency (RF) modulator using current-mode digital-to-analog converter (DAC) with idle current is proposed and fabricated in 90-nm complementary metal oxide semiconductor (CMOS) process. Since the proposed modulator directly converts digital base band (BB) parallel input signal into RF signal, small die size and low dc operation can be achieved. To reduce the higher order distortion components at the RF output, idle current is provided to BB current output from the current-mode DAC. By providing idle current of 10% of full scale DAC output current, 2nd and 3rd order distortion components near 5 GHz-band carrier are reduced and the improvement of effective number of bits (ENOB) is achieved. Measured ENOB of 6.36 bit (spurious-free dynamic range (SNDR) of 40.0 dB) with RF modulated output power of -28.4 dBm is obtained at 5 GHz. The core size of the proposed modulator integrated circuit (IC) is 200μm × 200μm. The dc power consumption of core circuit excluding inverter section for digital BB signal converter is 2.5 mW (2.1 mA/1.2 V).

Area-selective AI CVD technology has an excellent potential for filling via and contact holes of multilevel interconnection in Si ULSI. In this article, we discuss the selective AI CVD using metalorganic sources of trimethylaluminum [(CH 3 ) 3 AI, TMA] and dimethylaluminum hydride [(CH 3 ) 2 AIH, DMAH]. In order to deposit AI from TMA, the TMA molecule should be selectively excited into a reactive species of (CH 3 ) 2 AI in the well controlled H 2 /rf plasma. When using DMAH and H 2 , AI can be deposited by low-pressure CVD; the features are (1) single crystal AI on Si surface, (2) filling capability into 0.3 μmΦ/1 μm-deep contact holes, (3) low contact resistivity (2 × 10 −7 Ωcm 2 ) to n + − Si, and (4) erosion free at the Al/Si interface after 450 °C/30 min annealing. As a selective AI growth mechanism on the Si surface, we have proposed and experimentally confirmed a “surface electrochemical reaction model”. In this model, terminated-H on the Si surface reacts with CH 3 -radical of the DMAH molecule to produce volatile CH 4 . The H atom of the DMAH remains on the newly deposited AI surface as a newly terminated-H atom. The terminated-H atom on the surface reacts repeatedly with CH 3 -radical to deposit AI. It is noted that, in the DMAH molecule, two CH 3 -radicals and one H atom are bonded to AI atom, i.e. “asymmetric” structure. Since the different radicals are bonded to the AI atom, AI can be selectively and repeatedly deposited on Si surface. The precursor which has “asymmetric” structure is considered to have an important role for selective growth.

筆者らは,超LSIの微細配線金属形成技術への応用を目的にジメチルアルミニウムハイドライド(DMAH)を用いた選択Al CVD技術を開発してきた。本CVDの特徴は,Siなどの導電性基板表面にはAlが堆積し,SiO2Oなどの非導電性基板表面には堆積しない選択成長が可能なことである。また,特にSi上へは単結晶Alが堆積する。Si上への選択堆積に関して,「表面電気化学反応モデル」を提案し,実験的に検証してきた。表面に存在する自由電子の触媒的寄与により,単原子層終端水素とDMAHのメチル基が反応し,メタンとなって脱離し,Alが堆積する。堆積したAl表面は水素で終端され,終端水素とメチル基が反応・脱離し,Al堆積反応が持続するというモデルである。われわれは,このモデルをもとに,Si表面の単原子終端水素層を電子ビームでパターニングすると照射部分の水素は脱離し,Si表面は酸化し,Al堆積のマスクとなることを利用して,終端水素の残った部分のみにAlを堆積させる「アトミック水素レジストプロセス」を開発した。本稿では,選択Al CVD技術,選択成長メカニズム,さらにアトミックレジストプロセスによるAlパターニングについて紹介する。

We have proposed a theoretical design method for the lower boundary of supply voltage using the universal Eb/N0-bit error rate (BER) characteristics from the system viewpoint. In order to achieve the system error rate of less than 10-10 with the conditions of 10 years term, 10 GHz clock and 106 gate, the bit error rate of a gate should be less than 10-34. For a BER of 10-34, VDD should be larger than 0.1 V for 0.13 µm complementally metal-oxide-silicon (CMOS) LSI. For 0.05 µm CMOS of next generation, VDD should be larger than 0.2 V under the ideal thermal noise environment. The measured Eb/N0-BER characteristics of CMOS circuits as a function of supply voltage have agree well with the theoretical value.

A novel planar type broadband balun having a symmetrical structure has been proposed. Considering a lossless and uniform material, balun operation is analyzed and impedance matching condition is formulated. Applying the proposed balun configuration, and using CMOS multi-layer structure, a CMOS on-chip balun has been fabricated. The fabricated balun has achieved ultra-broadband performance. Measured characteristics of the balun are return loss of more than 8dB, insertion loss of 1.5 ∼ 6.3dB from the unbalanced to the balanced ports, and the amplitude difference and phase difference between the balanced ports of −0.2 ∼ +1.5dB and 173.5 ∼ 179deg, respectively, over the frequency range of 13 ∼ 110GHz.

Using 60-GHz band, multi-GHz bandwidth can be achieved for wireless personal area network (WPAN). However, WPAN requires high gain wide coverage area phased array antenna (PAA) for practical uses. In measurement of PAA, 3-D radiation pattern measurement is preferred. However, 2-D measurement is usually used because of limitations of measurement system. In this work, we propose a measurement method that can reduce measurement time for PAA while providing all radiation patterns; and a fixture to measure the 3-D radiation pattern which is compact and provides low interference on antenna's radiation pattern.

A low cost, small size antenna integrated transceiver module is one of the key technologies for the diffusion of short range millimeter-wave wireless communication. In this paper, 60GHz antenna integrated module technology is introduced, which based on 3-D system in package (SiP) technology. This module has a multi-level stacked organic substrates configuration. The use of low cost / low dielectric constant organic multi-layer substrates, stud bump bonding (SBB) for RFIC/MMIC flip-chip mounting and Cu ball interconnection for multi-level organic substrate stacking enable to realize low production cost and small size transceiver modules. Thank to the lower dielectric constant of organic substrate than that of conventional ceramic substrate, integration of antenna into the RF module becomes easy. The realization of phased array anttena module using same structure is also described.

For millimeter wave beam forming system, instead of using phase shifter at very high frequency of radio frequency (RF) or local oscillator (LO) frequency, low frequency baseband (BB) phase shifter has more potential for realization. Conventional BB phase shifters use variable gain amplifiers (VGA), which have low linearity, and calibration is required for over 3-bit BB phase shifters. In this paper, we propose a novel BB phase shifter using fixed gain amplifiers (FGA) matrix with in/out-phase switches. Since FGA normally has higher linearity than VGA, it is possible to reduce overall power consumption to achieve same linearity. FGA has fixed reflection and transfer characteristic, so mismatch between phase shift states are reduced. By dividing phase shifter into smaller stages, the effects of process mismatches on very nearby transistors are small. So proposed structure has robustness against process mismatch. Fabricated 5-bit BB phase shifter using proposed method has a very low power consumption to achieve almost same linearity as other works and has a 3-dB bandwidth of 1.2 GHz, 1.5° of rms phase error, lower than 0.2 dB of rms gain error without calibration. For ambient temperature from −20 °C to 80°C, simulated rms phase error varied by only 0.2°, and did not vary with process mismatch.